This invention relates to liquid filters, and more particularly to filters of the type having removeable and replaceable filter cartridges. Even more particularly, this invention relates to an improved filter housing which contains a replaceable filter cartridge containing two pleated filter packs, and which is designed to permit reuse of the filter housing after the filter packs have been replaced.
It has long been standard practice to design fluid filter units with replaceable filter cartridges, which after prolonged use become clogged or otherwise so dirty that the flow of fluid through the cartridges becomes so reduced that continued, incoming fluid dangerously increases the pressure created in the associated filter housing. It has therefore become quite commonplace to remove the filter elements or cartridges from a filter housing either to replace or to clean the elements for reuse. This presupposes, of course, that the interior of the filter housing is readily accessible to permit replacement of the filter cartridge or cartridges therein. For example, U.S. Pat. Nos. 2,654,483, 1,624,832 and 3,487,940 disclose filter units having replaceable filter elements and associated filter housings which can be used repeatedly upon the replacement of the associated filter elements therein. However, a major disadvantage of several filter units of the type described is that many such filter cartridges, such as disclosed for example in U.S. Pat. Nos. 5,180,489 and 5,811,002, are of the disposable type, which, when they become clogged and inoperative, are replaced by a new, similar cartridge, and the old cartridge is discarded, including, very often the entire cartridge housing and its contents.
It is an object of this invention, therefore, to provide an improved filter of the type which is designed so that the filter elements within the housing of an associated filter cartridge can be readily replaced, without requiring disposal of the housing of the cartridge itself, thereby considerably reducing the replacement costs of cartridges of the type that otherwise require disposal of the entire cartridge housing and its contents.
Still another object of this invention is to provide an improved filter unit of the type described having two pleated filter packs forming a replaceable filter cartridge enclosed in a perforated metal jacket which can be repeatedly employed after the filter packs have been replaced.
Another object of this invention is to employ an improved filter unit of the type described in which the replaceable filter elements thereof can be readily crushed and considerably reduced in size or alternatively can be incinerated.
Still other objects of this invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.
The filter unit includes a pair of metallic, tubular filter elements each of which has therethrough intermediate its ends numerous closely spaced circular openings. Although these perforated elements are equal in length, one is larger in diameter than the other and is referred to as the housing, while the other is denoted as the core.
In use the two perforated elements are releasably secured at opposite ends thereof, and in radially spaced coaxial relation to each other, in registering, annular recesses formed in the confronting surface of a pair of rigid end plates that are secured releasably over opposite ends of the elements by a plurality of steel support rods. Removably mounted in the annular space between the outer element or housing and the inner element or core, is a replaceable filter cartridge comprising a pair of radially spaced, pleated filter elements opposite ends of which are secured or potted in a pair of plastic end caps which are removably positioned between the housing and core with the outer surfaces thereof releasably and snugly engaging the inner surfaces of the end plates.